1. Field of the Invention
The present invention relates to a golf ball having a polyurethane cover and a method for producing the same, more specifically to technology for improving abrasion-resistance and controllability of the golf ball.
2. Description of the Related Art
As the base resin constituting the cover of the golf ball, an ionomer resin and a polyurethane resin are used. The cover using the ionomer resin is widely used because they are excellent in resilience, durability, processability or the like. There have been pointed out problems of poor shot feeling, insufficient spin performance, and inferior controllability since the ionomer resin cover has high rigidity and hardness. On the other hand, a polyurethane resin is used as a base resin constituting a cover because it provides improved shot feeling and spin performance compared with the ionomer resin. In recent years, however, accompanied with reduction of a thickness of a golf ball cover (thinner cover) and improvement of golf clubs (higher repulsion, lower spin, and change in groove configuration of face), there has been a demand for further improving cover performance of a golf ball, because abrasion-resistance and spin performance of a cover using a conventional polyurethane resin are no longer at a satisfactory level.
In view of such circumstances, for example, Japanese patent publication Nos. 2002-136618A, 2002-539905T, 2003-511116T, 2006-43447A and 2004-504900T propose improving cover properties by blending a filler such as an organic short fiber, a glass, a metal, and a clay mineral in a base resin constituting a cover. Additionally, technology for improving a mechanical property of polyurethane is disclosed in, for example, Japanese patent publication No. H10-168305A and Korean patent publication No. 2005-0112693. Further, Japanese patent publication No. 2008-289674A discloses a golf ball wherein the cover comprises a polyurethane resin having a secondary or tertiary amine structure in a molecular chain thereof and a layered silicate.